215 lines
7.4 KiB
Python
215 lines
7.4 KiB
Python
# SPDX-FileCopyrightText: 2023 James R. Barlow
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# SPDX-License-Identifier: MPL-2.0
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"""OCRmyPDF page processing pipeline functions."""
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from __future__ import annotations
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import logging
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import os
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from datetime import datetime, timezone
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from pathlib import Path
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from typing import Any
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from pikepdf import Dictionary, Name, Pdf
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from pikepdf import __version__ as PIKEPDF_VERSION
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from pikepdf.models.metadata import PdfMetadata, encode_pdf_date
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from ocrmypdf._defaults import PROGRAM_NAME
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from ocrmypdf._jobcontext import PdfContext
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from ocrmypdf._version import __version__ as OCRMYPF_VERSION
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from ocrmypdf.languages import iso_639_2_from_3
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log = logging.getLogger(__name__)
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def get_docinfo(base_pdf: Pdf, context: PdfContext) -> dict[str, str]:
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"""Read the document info and store it in a dictionary."""
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options = context.options
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def from_document_info(key):
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try:
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s = base_pdf.docinfo[key]
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return str(s)
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except (KeyError, TypeError):
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return ''
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pdfmark = {
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k: from_document_info(k)
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for k in ('/Title', '/Author', '/Keywords', '/Subject', '/CreationDate')
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}
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if options.title:
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pdfmark['/Title'] = options.title
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if options.author:
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pdfmark['/Author'] = options.author
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if options.keywords:
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pdfmark['/Keywords'] = options.keywords
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if options.subject:
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pdfmark['/Subject'] = options.subject
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creator_tag = context.plugin_manager.hook.get_ocr_engine().creator_tag(options)
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pdfmark['/Creator'] = f'{PROGRAM_NAME} {OCRMYPF_VERSION} / {creator_tag}'
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pdfmark['/Producer'] = f'pikepdf {PIKEPDF_VERSION}'
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pdfmark['/ModDate'] = encode_pdf_date(datetime.now(timezone.utc))
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return pdfmark
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def report_on_metadata(options, missing):
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if not missing:
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return
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if options.output_type.startswith('pdfa'):
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log.warning(
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"Some input metadata could not be copied because it is not "
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"permitted in PDF/A. You may wish to examine the output "
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"PDF's XMP metadata."
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)
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log.debug("The following metadata fields were not copied: %r", missing)
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else:
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log.error(
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"Some input metadata could not be copied."
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"You may wish to examine the output PDF's XMP metadata."
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)
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log.info("The following metadata fields were not copied: %r", missing)
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def repair_docinfo_nuls(pdf):
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"""If the DocumentInfo block contains NUL characters, remove them.
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If the DocumentInfo block is malformed, log an error and continue.
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"""
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modified = False
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try:
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if not isinstance(pdf.docinfo, Dictionary):
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raise TypeError("DocumentInfo is not a dictionary")
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for k, v in pdf.docinfo.items():
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if isinstance(v, str) and b'\x00' in bytes(v):
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pdf.docinfo[k] = bytes(v).replace(b'\x00', b'')
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modified = True
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except TypeError:
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# TypeError can also be raised if dictionary items are unexpected types
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log.error("File contains a malformed DocumentInfo block - continuing anyway.")
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return modified
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def should_linearize(working_file: Path, context: PdfContext) -> bool:
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"""Determine whether the PDF should be linearized.
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For smaller files, linearization is not worth the effort.
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"""
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filesize = os.stat(working_file).st_size
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if filesize > (context.options.fast_web_view * 1_000_000):
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return True
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return False
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def _fix_metadata(meta_original: PdfMetadata, meta_pdf: PdfMetadata):
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# If xmp:CreateDate is missing, set it to the modify date to
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# ensure consistency with Ghostscript.
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if 'xmp:CreateDate' not in meta_pdf:
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meta_pdf['xmp:CreateDate'] = meta_pdf.get('xmp:ModifyDate', '')
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if meta_pdf.get('dc:title') == 'Untitled':
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# Ghostscript likes to set title to Untitled if omitted from input.
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# Reverse this, because PDF/A TechNote 0003:Metadata in PDF/A-1
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# and the XMP Spec do not make this recommendation.
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if 'dc:title' not in meta_original:
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del meta_pdf['dc:title']
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def _unset_empty_metadata(meta: PdfMetadata, options):
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"""Unset metadata fields that were explicitly set to empty strings.
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If the user explicitly specified an empty string for any of the
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following, they should be unset and not reported as missing in
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the output pdf. Note that some metadata fields use differing names
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between PDF/A and PDF.
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"""
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if options.title == '' and 'dc:title' in meta:
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del meta['dc:title'] # PDF/A and PDF
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if options.author == '':
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if 'dc:creator' in meta:
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del meta['dc:creator'] # PDF/A (Not xmp:CreatorTool)
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if 'pdf:Author' in meta:
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del meta['pdf:Author'] # PDF
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if options.subject == '':
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if 'dc:description' in meta:
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del meta['dc:description'] # PDF/A
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if 'dc:subject' in meta:
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del meta['dc:subject'] # PDF
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if options.keywords == '' and 'pdf:Keywords' in meta:
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del meta['pdf:Keywords'] # PDF/A and PDF
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def _set_language(pdf: Pdf, languages: list[str]):
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"""Set the language of the PDF."""
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if Name.Lang in pdf.Root or not languages:
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return # Already set or can't change
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primary_language_iso639_3 = languages[0]
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if not primary_language_iso639_3:
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return
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iso639_2 = iso_639_2_from_3(primary_language_iso639_3)
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if not iso639_2:
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return
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pdf.Root.Lang = iso639_2
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class MetadataProgress:
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def __init__(self, progressbar_class, enable: bool = True):
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self.progressbar_class = progressbar_class
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self.progressbar = self.progressbar_class(
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total=100, desc="Linearizing", unit='%', disable=not enable
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)
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def __enter__(self):
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self.progressbar.__enter__()
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return self
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def __exit__(self, exc_type, exc_value, traceback):
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return self.progressbar.__exit__(exc_type, exc_value, traceback)
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def __call__(self, percent: int):
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if not self.progressbar_class:
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return
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self.progressbar.update(completed=percent)
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def metadata_fixup(
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working_file: Path, context: PdfContext, pdf_save_settings: dict[str, Any]
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) -> Path:
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"""Fix certain metadata fields whether PDF or PDF/A.
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Override some of Ghostscript's metadata choices.
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Also report on metadata in the input file that was not retained during
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conversion.
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"""
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output_file = context.get_path('metafix.pdf')
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options = context.options
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pbar_class = context.plugin_manager.hook.get_progressbar_class()
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with (
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Pdf.open(context.origin) as original,
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Pdf.open(working_file) as pdf,
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MetadataProgress(pbar_class, options.progress_bar) as pbar,
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):
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docinfo = get_docinfo(original, context)
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with (
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original.open_metadata(
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set_pikepdf_as_editor=False, update_docinfo=False, strict=False
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) as meta_original,
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pdf.open_metadata() as meta_pdf,
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):
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meta_pdf.load_from_docinfo(
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docinfo, delete_missing=False, raise_failure=False
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)
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_fix_metadata(meta_original, meta_pdf)
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_unset_empty_metadata(meta_original, options)
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_unset_empty_metadata(meta_pdf, options)
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meta_missing = set(meta_original.keys()) - set(meta_pdf.keys())
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report_on_metadata(options, meta_missing)
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_set_language(pdf, options.languages)
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pdf.save(output_file, progress=pbar, **pdf_save_settings)
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return output_file
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